<title>High-resolution imaging with multilayer telescopes: resolution performance of the MSSTA II telescopes</title>

Abstract

The Multi-Spectral Solar Telescope Array (MSSTA) is a sounding rocket-borne observatory composed of a set of normalincidence multilayer-coated telescopes that obtained selected bandpass spectroheliograms (44A -1550A) of the Solar atmosphere. These spectroheliograms were recorded on specially fabricated XUV and FUV 70mm Kodak film. Rocket launches of this instrument payload took place in 1991 (MSSTA 1) and 1994 (MSSTA II) at the White Sands Missile Test Range in New Mexico, sponsored by the NASA sounding rocket experiment program. Immediately prior to the 1994 launch, visible light focusing tests of each telescope were performed in-situ using a 195 1 Standard Air Force High Resolution Testtarget, to measure optical resolution performance. We determined that the MSSTA II telescopes performed at diffractionlimited resolutions down to 0.70 arc-second at visible wavelengths. Based on these measurements, we calculated an upperbound to the focusing errors that incorporate the sum of all uncorrelated system resolution errors that affect resolution performance. Coupling these upper-bound estimates with the in-band diffraction limits, surface scattering errors and payload pointing jitter, we demonstrate that eleven of nineteen MSSTA II telescopeshaving negligible figures of focus errors in comparison to the corresponding visible diffraction limitsperformed at sub arc-second resolution at their operational FUV/EUV/XUV wavelengths during flight. We estimate the in-band performance down to 0.14 0.08 second of arc. Downloaded From: http://proceedings.spiedigitallibrary.org/ on 03/03/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx measurement of the in-band point spread function was not performed as it is a difficult and expensive measurement to conduct properly.Prior to the initial flight of multilayer telescopes in wavelength bands centered at I 73A and 256A, the Stanford-MSFC-LLNL consortium carried out a resolution test on a specially prepared Cassegrain telescope at 44.3A (identical to the 173A Cassegrain) using multilayer mirrors designed to reflect the C Ka line. These tests were carried out in the MSFC Xray Calibration Facility (XRCF) by Lindblom et al., 10, 11 who showed that the resolution of the multilayer mirrors was limited by the aberrations of the mirror substrates and also because of a mechanical deformation of the primary mirror introduced by its holding mechanism. Although efficiency tests have been carried out on all multilayer optical systems subsequently flown, the difficulty and expense of fabricating optical testing systems that can image the characteristic soft xray and EUV wavelengths that can be generated with laboratory sources, has precluded in-band resolution testing. Instead, we have carried out resolution tests at optical wavelengths using laser interferometric techniques to verify the optical figure, alignment and spatial frequency response of our flight telescopes. Coupled with these interferometric tests, visible light imaging measurements using a calibrated, standard high r...

Implausibility of Hydrostatic Funnels Constituting the Sun’s Upper Transition Region

“…The spectroheliograms used were in the emission of H Ly α obtained in 1991 by the Multi-Spectral Solar Telescope Array (MSSTA) and in a passband centered on the C IV multiplet at 1550 Å but dominated by a strong 1600 Å continuum component from the temperature minimum, obtained by the MSSTA in 1994 (Oluseyi et al, 1999a). The spatial resolution of both these observations was ≈ 1 (Allen et al, 1997;Martinez-Galarce et al, 2000). The 1994 temperature-minimum image also had a simultaneous image in H Ly α.…”

The high-resolution lightweight telescope for the EUV (HiLiTE)

“…The telescope structure has been designed to fit inside the existing Multi-Spectral Solar Telescope Array (MSSTA) rocket truss, which flew three times between 1991 and 2002 7,8 . We conducted finite element analysis of the design in this configuration in order to assess the instrument's performance in a rocket flight; see Figure 2.…”

The Solar Chromosphere/Corona Interface. I. Far‐Ultraviolet to Extreme‐Ultraviolet Observations and Modeling of Unresolved Coronal Funnels

“…Allen et al (1994), Deforest (1995), Kankelborg (1996), and Martínez-Galarce (2000) describe these payload instruments in detail. For a comprehensive summary of the MSSTA II payload and its performance, we refer the reader to the analysis given by Martínez-Galarce et al (2000), and to the references therein.…”

“…In spring 2002, MSSTA III, renamed the Chromospherical/Coronal Spectroheliograph (CCS), and consisting of another complement of new instruments, is scheduled for flight (Boerner et al 2000). The CCS will carry 11 imaging instruments.…”

“…Rabin, on the other hand, was successful in finding a funnel model with modest constriction, À $ 4, and within the 10 5 -10 6 K regime, that fit the differential emission measure estimates determined by Raymond & Doyle. In the present analysis, we adopt the model proposed by Rabin (1991) and test it against a set of spectroheliograms recorded on board a sounding-rocket flight in 1994. The instrument payload, called the Multi-Spectral Solar Telescope Array II (MSSTA II) consisted of several multilayer telescopes designed to image the solar atmosphere in specific narrow bandpasses in the far-ultraviolet (FUV), extremeultraviolet (EUV), and soft X-ray wavelengths (Martínez-Galarce et al 2000). In particular, two spectroheliograms from this flight are used for our analysis.…”